Not everyone has time to hop on a video call in your last few days, so at least send a personalized thank-you message via email or on Slack.
Put time and thought into each message, as every person you worked with had a different relationship and experience with you. Think about all of the unique opportunities you had to grow with them and incorporate that into your goodbye.
For example, this is the gist of a message I sent to the person who edited this article:
Thank you for helping me grow into a better editor. You taught me so much about organizing, framing, and compiling a thorough story with [story or project you worked closely on]; I feel so much more confident in my abilities thanks to you. I wish we could have had longer together!
I'd love to keep in touch and hopefully see you in person once this is all through. I'm going to continue reading what this team puts out and look forward to seeing everything you guys do once I leave. If there's anything I can ever do for you or the team, or if you ever just want to chat, please don't hesitate to contact me at [cellphone number] or [email address]. And please let me know what's the most convenient way to reach you; I would love to hear how you're doing, even if I'm no longer working here.
I sincerely can't thank you enough: I'm going to miss working with you. My best to you and your kids through these crazy times!
Something simple that clearly outlines the specific ways they've helped you and that you want to keep in touch helps people understand how grateful you were for their time and expertise. Definitely leave your contact information and ask for theirs; doing so shows that you actually intend to talk to them beyond your internship, and not just about work.
After sending individual notes, make sure you leave the best way to reach you in one official group email, too. There's no such thing as saying "thank you" too many times.